Forty-four subjects, who at the age of 4 years had been treated for unilateral forced cross-bite by grinding or by maxillary arch expansion, were 16-19 years later followed-up by means of a questionnaire about their present condition with regard to temporomandibular disorders (TMD). Twenty-two of them had received only early treatment (early questionnaire group) and 22 had received late treatment (late questionnaire group). Fourteen of the subjects who received late treatment also received early treatment. Twenty-nine of the subjects were also examined clinically. Eighteen of these had only received early treatment at 4 years of age (early clinical group), whereas 11 of them also received later treatment in the mixed or permanent dentition because of relapse (late clinical group). No significant differences were found between the early and late groups with regard to signs and symptoms of TMD. Most of the young adults who had undergone orthodontic treatment had well-functioning masticatory systems, and severe TMD signs and symptoms were rare. The results of this study suggest that relapse of early orthodontic treatment and further need of treatment does not influence the later status of subjective symptoms or clinical signs of TMD in young adults.